CD74 and spondyloarthropathy: CD74 is a chaperone of the major histocompatibility complex‐II, which has been demonstrated to play important roles in many inflammatory and autoimmune diseases, such as kidney diseases [42], liver fibrosis [43], cardiovascular diseases [44], cancers [45, 46, 47], infections [48], autoimmune encephalomyelitis [49], spondyloarthritis [50], and SLE [51, 52].